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Commit | Line | Data |
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1 | /* | |
2 | * Access kernel memory without faulting. | |
3 | */ | |
4 | #include <linux/uaccess.h> | |
5 | #include <linux/module.h> | |
6 | #include <linux/mm.h> | |
7 | ||
8 | /** | |
9 | * probe_kernel_read(): safely attempt to read from a location | |
10 | * @dst: pointer to the buffer that shall take the data | |
11 | * @src: address to read from | |
12 | * @size: size of the data chunk | |
13 | * | |
14 | * Safely read from address @src to the buffer at @dst. If a kernel fault | |
15 | * happens, handle that and return -EFAULT. | |
16 | */ | |
17 | long probe_kernel_read(void *dst, void *src, size_t size) | |
18 | { | |
19 | long ret; | |
20 | mm_segment_t old_fs = get_fs(); | |
21 | ||
22 | set_fs(KERNEL_DS); | |
23 | pagefault_disable(); | |
24 | ret = __copy_from_user_inatomic(dst, | |
25 | (__force const void __user *)src, size); | |
26 | pagefault_enable(); | |
27 | set_fs(old_fs); | |
28 | ||
29 | return ret ? -EFAULT : 0; | |
30 | } | |
31 | EXPORT_SYMBOL_GPL(probe_kernel_read); | |
32 | ||
33 | /** | |
34 | * probe_kernel_write(): safely attempt to write to a location | |
35 | * @dst: address to write to | |
36 | * @src: pointer to the data that shall be written | |
37 | * @size: size of the data chunk | |
38 | * | |
39 | * Safely write to address @dst from the buffer at @src. If a kernel fault | |
40 | * happens, handle that and return -EFAULT. | |
41 | */ | |
42 | long notrace __weak probe_kernel_write(void *dst, void *src, size_t size) | |
43 | { | |
44 | long ret; | |
45 | mm_segment_t old_fs = get_fs(); | |
46 | ||
47 | set_fs(KERNEL_DS); | |
48 | pagefault_disable(); | |
49 | ret = __copy_to_user_inatomic((__force void __user *)dst, src, size); | |
50 | pagefault_enable(); | |
51 | set_fs(old_fs); | |
52 | ||
53 | return ret ? -EFAULT : 0; | |
54 | } | |
55 | EXPORT_SYMBOL_GPL(probe_kernel_write); |